The invention relates to a process for allowing the attachment of drive or coupling elements, such as cams, gears, crank webs, or bearing elements, such as friction bearing bushes or complete roller bearings, on tubes or tubular portions, by hydraulic expansion of the tube in the region of the respective element beyond the limit of elasticity against an elastic prestress prevailing in the respective elements. The hydraulic expansion is accomplished by means of a pressure agent probe comprising effective portions which are associated with the respective elements to be attached, which are limited by seals and which, via a first probe borehole system, are connected to a pressure agent generator. The pressure agent probe also has intermediate portions between the individual effective portions, which are in contact with a second probe borehole system, and end portions adjoining the respective outermost effective portions. The effective portions form effective regions with the tube, the intermediate portions form intermediate regions with the tube and the end portions form end regions with the tube.
From DE 37 26 083 A1 (Balcke-Durr) a pressure agent probe is known which comprises two independent borehole systems the first of which, for pressurizing the effective regions, is connected to a pressure agent generator, and the second system, by being connected to the intermediate portions, serves to drain off any leakages, especially when some of the seals fail. The process which may be carried out with these means is characterized by the pressure build-up in the effective regions up to a point where the limit of elasticity of the tubular portions concerned is exceeded, and the subsequent pressure decreases. Accordingly, the pressure generator comprises an exit which is directly connected to the first borehole system of the pressure agent probe.
The essential problem of the prior art processes relates to the lack of operating safety of the seals, especially with increasingly larger shaft types to be produced by this process the necessary pressures increase further.